Combining per-aqueous and chiral reversed phase separation modes towards an enhanced comprehensive 2-dimensional liquid chromatographic based chiral screening platform.

The differentiation of enantiomers in complex mixtures is crucial in various fields such as food science, pharmaceuticals, and environmental studies. While this is achievable in principle through comprehensive two-dimensional liquid chromatography (LC × LC), practical challenges emerge when the mobile phase used in the first dimension (D) is too strong or incompatible with the one in the second dimension (D), leading to peak broadening and reduced resolution. These drawbacks become particularly evident when analyzing a diverse range of chiral compounds.

Prediction of Retention Indices in LC-HRMS for Enhanced Structural Identification of Organic Micropollutants in Water: Selectivity-Based Filtration.

Addressing the global challenge of ensuring access to safe drinking water, especially in developing countries, demands cost-effective, eco-friendly, and readily available technologies. The persistence, toxicity, and bioaccumulation potential of organic pollutants arising from various human activities pose substantial hurdles. While high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS) is a widely utilized technique for identifying pollutants in water, the multitude of structures for a single elemental composition complicates structural identification.

Maximizing sensitivity and selectivity in LC × LC-HRMS for pesticide analysis via exploitation of per-aqueous liquid chromatography.

Accurate monitoring of pesticide residues at minimal concentrations is imperative for adherence to stringent regulatory standards in numerous countries. This study presents an innovative methodology employing comprehensive two-dimensional liquid chromatography coupled with high-resolution mass spectrometry (LC × LC-HRMS). The approach ensures high sensitivity and selectivity in detecting targeted compounds.

2D-CEX-FcRn-MS to Study Structure/Function Relation of mAb Charge Variants.

The automated elucidation of the interplay between monoclonal antibody (mAb) structure and function using two-dimensional liquid chromatography-mass spectrometry (2D-LC-MS) is reported. Charge variants, induced through forced degradation, are resolved by first-dimension (D) cation-exchange chromatography (CEX) and subsequently collected in loops installed on a multiple heart-cutting valve prior to transfer to second-dimension (D) neonatal crystallizable fragment receptor (FcRn) affinity chromatography coupled with MS. As such, binding affinity of the latter mAb variants can elegantly be assessed and a first glimpse of identity provided.

Exploring the Effects of Optically Active Solvents in Chiral Chromatography on Polysaccharide-Based Columns.

Exploring the effectiveness of optically active solvents as mobile-phase modifiers in chiral liquid chromatography (LC) can offer an additional new tool to tune the chiral selectivity. Hence, the potential of l-ethyl lactate (LEL), a biobased solvent of this nature, was explored for its distinctive interactions with both the mobile phase and analytes, as anticipated from its chiral nature. The findings reveal that LEL provides distinct selectivity compared to commonly used modifiers in chiral LC.

Physicochemical modelling of the retention mechanism of temperature-responsive polymeric columns for HPLC through machine learning algorithms.

Temperature-responsive liquid chromatography (TRLC) offers a promising alternative to reversed-phase liquid chromatography (RPLC) for environmentally friendly analytical techniques by utilizing pure water as a mobile phase, eliminating the need for harmful organic solvents. TRLC columns, packed with temperature-responsive polymers coupled to silica particles, exhibit a unique retention mechanism influenced by temperature-induced polymer hydration. An investigation of the physicochemical parameters driving separation at high and low temperatures is crucial for better column manufacturing and selectivity control.

Chemical compositions of Eucalyptus sp. Essential oils and the evaluation of their combinations as a promising treatment against ear bacterial infections.

Background: The chemical composition and biological activities of Eucalyptus essential oils (EOs) have been documented in numerous studies against multiple infectious diseases. The antibacterial activity of individual Eucalyptus EOs against strains that cause ear infections was investigated in our previous study. The study's antibacterial activity was promising, which prompted us to explore this activity further with EO blends.

Multidimensional LC-MS with D multi-method option and parallel middle-up and bottom-up MS acquisition for in-depth characterization of antibodies.

Monoclonal antibodies (mAbs) are large and highly heterogeneous species typically characterized using a plethora of analytical methodologies. There is a trend within the biopharmaceutical industry to combine several of these methods in one analytical platform to simultaneously assess multiple structural attributes. Here, a protein analyzer for the fully automated middle-up and bottom-up liquid chromatography-mass spectrometry (LC-MS) analysis of charge, size and hydrophobic variants is described.

Temperature-responsive comprehensive two-dimensional liquid chromatography coupled to high resolution mass spectrometry for the elucidation of the oxidative degradation processes of chemicals of environmental concern.

This study explores the possibilities offered by temperature-responsive liquid chromatography (TRLC) based comprehensive 2-dimensional liquid chromatography in combination with reversed-phase liquid chromatography (RPLC) for the analysis of degradation products formed upon oxidative treatment of persistent organic pollutants, in this case exemplified through carbamazepine (CBZ). The TRLC×RPLC combination offers the possibility to overcome peak overlap and incomplete separation encountered in 1D approaches, while the transfer of the purely aqueous mobile phase leads to refocusing of all analytes on the second dimension column. Consequently, this allows for about method-development free and hence, easier LC×LC.

Into the toxicity potential of an array of parabens by biomimetic liquid chromatography, cell viability assessments and in silico predictions.

Five parabens (PBs) i.e., Methylparaben (MP), Ethylparaben (EP), Isopropylparaben (iPrP), Isobutylparaben (iBuP), Benzylparaben (BzP), and their parent compound i.

On-column modification for the creation of temperature-responsive stationary phases.

Temperature-responsive liquid chromatography (TRLC) offers an alternative for retention and selectivity optimisation in HPLC. This approach thereby exploits temperature gradients on stimuli-responsive stationary phases and forfeits the necessity for solvent gradients, allowing analyses to be performed using aqueous mobile phases. Consequently, it can be employed as a green alternative to reversed-phase separations.

Polysaccharide metabolism in Anacardiaceae (Asian lacquer) cross-linked polymers elucidated using in situ trimethylsilylation pyrolysis-gas chromatography-mass spectrometry.

Carbohydrates from polysaccharides in natural thermoset Anacardiaceae polymers of Gluta usitata, Toxicodendron succedaneum and Toxicodendron vernicifluum were identified using pyrolysis-gas chromatography-mass spectrometry with in situ trimethylsilylation. Pyrolysates resulting from the pyrolytic intermolecular chain scission of the polysaccharides were used to elucidate monomeric units. Polysaccharides, dispersed in the phenolic lacasse catalysed cross-linked macromolecules, showed to be metabolised through various catabolic and anabolic routes.

High-throughput and reliable assessments of the ionization constant of monoprotic organic acids through an arginine based mixed mode HPLC.

The charge state of a molecule is the single most prominent attribute ruling out its interactions with the surrounding environment. In a previous study, the retention of acids on the new Celeris™ Arginine (ARG) column was found to be predominantly driven by electrostatics and, specifically, their charge state. Therefore, we analysed 41 compounds in liquid chromatography with ultraviolet detection to study possible relationships between the analytical retention on this phase and the pK of the acidic solutes.

Facilitating structural elucidation of small environmental solutes in RPLC-HRMS by retention index prediction.

Implementing effective environmental management strategies requires a comprehensive understanding of the chemical composition of environmental pollutants, particularly in complex mixtures. Utilizing innovative analytical techniques, such as high-resolution mass spectrometry and predictive retention index models, can provide valuable insights into the molecular structures of environmental contaminants. Liquid Chromatography-High-Resolution Mass Spectrometry is a powerful tool for the identification of isomeric structures in complex samples.

Temperature Responsive × Fast Chiral Comprehensive Liquid Chromatography: a New 2D-LC Platform for Resolving Mixtures of Chiral Isomers.

Chiral resolution of solutes occurring in mixtures of unrelated species is of relevance in life sciences and in pharmaceutical analysis. While this is conceptually achievable by comprehensive two-dimensional liquid chromatography (LC × LC), few approaches exist whereby the second dimension comprises the chiral separation. The latter is preferable in combination with a conventional reversed phase type of separation in the first dimension as it offers an extension of a conventional achiral analysis.

Enhanced Sensitivity in Comprehensive Liquid Chromatography: Overcoming the Dilution Problem in LC × LC via Temperature-Responsive Liquid Chromatography.

In comprehensive two-dimensional liquid chromatography (LC × LC), solvents of high eluotropic strength are frequently used in the first dimension (D), which lead to peak broadening in the second dimension (D). In the majority of the current LC × LC column combinations, analytes are less than optimally refocused upon transfer to the second column, which negatively affects sensitivity. Furthermore, the typical combination of 1 or 2.

Speeding up temperature-responsive × reversed-phase comprehensive liquid chromatography through the combined exploitation of temperature and flow rate gradients.

Comprehensive two-dimensional liquid chromatography (LC×LC) can provide enhanced resolving power and higher peak capacities for the separation of complex samples. The transfer of fractions of too high eluotropic strength from the first dimension, however, can lead to peak broadening. This process is related to the column dimensions, the flow rates, mobile phase compositions, and stationary phase compatibility.

Hyphenating temperature gradient elution with refractive index detection through temperature-responsive liquid chromatography.

Refractive index detection (RID) is attractive because it allows approaching the benefits of universal detection with liquid chromatography, by which ideally standard independent calibration and hence compound independent quantification becomes possible. Nevertheless, the implementation of RID has remained limited as it offers poor detection sensitivity while only being compatible with isocratic mobile phases. The implementation of compositional solvent gradients has remained prohibitively challenging in commercial HPLC-RID systems due to the resulting drastic alterations in refractive index and extreme baseline drift.

3D-LC-MS with D Multimethod Option for Fully Automated Assessment of Multiple Attributes of Monoclonal Antibodies Directly from Cell Culture Supernatants.

Fully automated analysis of multiple structural attributes of monoclonal antibodies (mAbs) using three-dimensional liquid chromatography-mass spectrometry (3D-LC-MS) is described. The analyzer combines Protein A affinity chromatography in the first dimension (D) with a multimethod option in the second dimension (D) (choice between size exclusion (SEC), cation exchange (CEX), and hydrophobic interaction chromatography (HIC)) and desalting SEC-MS in the third dimension (D). This innovative 3D-LC-MS setup allows simultaneous and sequential assessment of mAb titer, size/charge/hydrophobic variants, molecular weight (MW), amino acid (AA) sequence, and post-translational modifications (PTMs) directly from cell culture supernatants.

Investigation of the potential of mixed solvent mobile phases in temperature-responsive liquid chromatography (TRLC).

Temperature-responsive liquid chromatography (TRLC) allows for extensive retention and selectivity tuning through temperature in HPLC. This is mainly achieved through the use of a stationary phases comprising of a temperature-responsive polymer which undergoes a reversible change from hydrophilic to hydrophobic behaviour upon increasing the temperature. The approach can allow for reversed phase type separations to be achieved with purely aqueous mobile phases, whereby the retention is controlled through temperature instead of mobile phase composition.

Comprehensive two-dimensional temperature-responsive × reversed phase liquid chromatography for the analysis of wine phenolics.

Phenolic compounds are an interesting class of natural products because of their proposed contribution to health benefits of foods and beverages and as a bio-source of organic (aromatic) building blocks. Phenolic extracts from natural products are often highly complex and contain compounds covering a broad range in molecular properties. While many 1D-LC and mass spectrometric approaches have been proposed for the analysis of phenolics, this complexity inevitably leads to challenging identification and purification.

Implementations of temperature gradients in temperature-responsive liquid chromatography.

Temperature Responsive Liquid Chromatography (TRLC) offers an alternative and environmentally friendly way to perform reversed-phase like separations. Its use of temperature responsive polymers to control retention based on column temperature, instead of the fraction of organic modifier in the mobile phase mobile, eliminates the need for solvent composition gradients and allows, for example, for purely aqueous separations. In principle this temperature induced retention should allow for gradient elutions to be performed using downward temperature gradients to control retention and refocus the analyte peaks.

Chemical composition of essential oils of eight Tunisian Eucalyptus species and their antibacterial activity against strains responsible for otitis.

Background: The chemical composition and biological activity of Eucalyptus essential oils have been studied extensively (EOs). A few of them were tested for antibacterial effectiveness against otitis strains. The chemical composition and antibacterial activity of the EOs of eight Tunisian Eucalyptus species were assessed in the present study.

Monoclonal antibody charge variant characterization by fully automated four-dimensional liquid chromatography-mass spectrometry.

Fully automated characterization of monoclonal antibody (mAb) charge variants using four-dimensional liquid chromatography-mass spectrometry (4D-LC-MS) is reported and illustrated. Charge variants resolved by cation-exchange chromatography (CEX) using a salt- or pH-gradient are collected in loops installed on a multiple heart-cutting valve and consequently subjected to online desalting, denaturation, reduction and trypsin digestion prior to LC-MS based peptide mapping. This innovation which substantially reduces turnaround time, sample manipulation, loss and artefacts and increases information gathering, is described in great technical detail, and applied to characterize the charge heterogeneity associated with three therapeutic mAbs.